Good Will in Internet Marketing is possible! I just did one!! - Need your thoughts

Folks, thought of sharing a memorable incident that happened couple of days back. Would like to know what you guys think about this.

Summary: I acquired a domain name. Few days later a gentle man from a non-profit organization claimed that the domain belongs to his company. He requested if they can have a deal with me in favor of returning the domain to them. I just returned for free!

More details in the e-mail chain: (Masked few details for privacy)
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Hello,

My name is XXXXX and I am the President of YYYYY. YYYYY is a non-profit children's charity based in Springfield VT. We had a web domain name that was set up for us by a third party person. We were not aware that the domain needed to be renewed so that we would not lose it. We have now found this out the hard way. From what GoDaddy.com shows you have purchased our domain name. What can we do to get this name back? Can we work out some sort of deal so that we may continue to use the domain YYYYY.com? Please feel to free to call me at xxx-xxx-xxxxx or email me. Thank you

Sincerely,
President YYYY
XXXX
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My Reply
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Hi XXXXX,

Thanks for writing to me. My name is Samuel and I am based out of NC. We are a professional domain flipping firm. i.e., We acquire domains and sell it for profit, which was the reason behind acquiring YYYYY.com

It is very unfortunate that you weren't aware of domain renewing process. Thankfully you have got in touch with me before I sold this domain.

If this domain would have been acquired by some other domainers, they would demand a minimum sum of $xx,xxx to transfer back to you. However I am not fully motivated by "money" as you are NGO. After much thoughts and prayers I have decided to return back this domain in good will for free.

Please send me your Godaddy customer number and associated e-mail address so that we can initiate domain push.

Good luck!
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His thankful reply
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Hello Samuel,

Thank you for getting back to me so quickly. I can not thank you enough for your generosity. I will personally make sure that this issue does not happen again. The information you asked for is this.

Customer acct. number <Removed>
Email for acct. <Removed>

Please let me know if there is anything else you need from me so that we can get this done. Again I really appreciate this.

Sincerely,
President YYYYY
XXXXX
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So, what do you guys think about this? Was it right from my part to transfer this domain back to him in good will? Or should I had priced him for this mistake? Pour out your thoughts please.